Archimedes Amplifiers

This is a special-order product and can not be ordered online. 

Please contact us to place an order for this product.

Years after collaborating on the hugely successful Arion Phono preamplifier and Axiom III line stage with Michael Bettinger, Luminous is extraordinarily proud to announce the new Archimedes power amplifiers. The units deliver 100 watts into 8 ohms with very high current and remarkably low output

impedance.

Designed with the soul/nuance of a tube power amplifier with the musical foundation and dynamics of higher power amplifier designs.

A JFET based input stage provides tube-like resolution and body to the music, and a balanced output stage and unique power supply design that imparts a seemingly limitless flow of pure power into your speakers.

The LAT Archimedes has the sonic muscle of solid-state amps coupled with the sonic DNA of tube designs.

A Tribute.

The LAT Archimedes is an evolution of the work of the late James Bongiorno, whose design output throughout his career reads like a who’s who of classic designs that are and still being sought after 50+ years later.

In the 1980’s James created the SUMO Electric Company where he produced some of his most brilliant and inventive rethinking of audio amplification. During his time at SUMO; The Power, The Gold, the Model Nine and Andromeda amplifiers were designed and produced. Later products including the SST Ampzilla 2000 and his work with Constellation Audio continued to advance James’s refinement of what is described as a Four Quadrant Differential amplifier. Many years of studying James’s designs have guided us in creating our version of this outstanding amplifier topology.

The Archimedes

While all the attributes listed above contribute to the musical quality of the Archimedes, the most audibly significant aspect of the LAT design is its Balance Drive. The circuit topology is fully balanced from input to output, with +/- loudspeaker connections of the loudspeaker (+/- terminals) driven in push-pull fashion by four identical outputs of a perfectly balanced differential amplifier (the four quadrants).

Why is this important? Because the loudspeaker is in essence a motor. Its designer chooses one form of technology (of many available) to create motion and sound from the application of power. Due to the motor’s inherent imperfections, the amplifier’s job is made a lot more difficult than it would appear.

While loudspeaker designers put a lot of design time and effort into making the load that their speakers present to the amplifier as benign as possible there are limits to the basic technology to contend with.

Specifically, the job of the amplifier is manifold. It must supply the power to move the loudspeaker. It must supply a reverse EMF for damping or control the motion of the loudspeaker, when necessary. This also requires the amplifier to absorb a tremendous amount of energy that is generated by the speaker drivers (known as back EMF) as the drivers try to oppose the power that the amplifier is delivering to the loudspeaker - analogous to the undertow of the waves breaking on a beach.

What the Balance Drive Technology brings to this picture is the ability to control the speaker drivers more effectively by locking its motion between a positive amplifier and a negative amplifier, allowing the amplifier to absorb the reactive power that is being generated by the speakers. Conventional and symmetrical amplifier designs must rely on a flawed power-supply ground to accomplish this necessary damping.

While there are additional benefits to this circuit topology, the wideband control of the speakers’ drivers due to the Balance Drive is a major benefit.

In the LAT Archimedes, the circuit layout and power supplies treat the four quadrants as four independent signal paths driving the two Class AB output stages driving the +/- speaker terminals.

The LAT Archimedes is our tribute to James Bongiorno, the man, and his genius. This amplifier is the essence of his work coupled with our experience and advances in current audio amplifier design technology.

-Michael Bettinger Nov 2022

Specifications:

• 100-watt monaural amplifiers
• JFET dual differential input stage
• Fully balanced VA and drive circuitry
• Dual class A/B power amp stages for independent pos/neg speaker drive
• Separate loop feedback from both +/- speaker outputs
• Independent power supplies: transformers, rectifiers, and filters for dual amp stages
• Dual high current power supplies and circuit layout, for low natural damping factor
• Complete isolation of circuitry layout for all four drive quadrants from differential stage through output stages
• Power Output: 100 Watts RMS into 8 Ohms both channels driven, 20hz to 20Khz, < 03% THD
• Output: Balanced drive.
• Output connections: 2 pairs multi-way binding posts
• Gain: 24 db
• Sensitivity: 1.8 V for rated output.
• Input: Single ended, line-level
• Input Impedance: 75K
• IM Distortion: < .03%
• Damping Factor: < 700 @ 20hz
• Signal to Noise: < 95 dB/full output, 20Hz-20Khz
• Frequency Response: 20Hz to 20Khz +/- .03dB
• Chassis: 6.7” (170mm) W X16” (405mm) D X 9.45” (240mm) H
• Weight: 22lbs.
• AC Line Voltage: 110/220 VAC, Preset during assembly.
• Shipped with Volex AC cord.

Archimedes Owners Manual